Monkeypox is now a global public health emergency, the head of the World Health Organization decided on Saturday. The viral disease is officially a Public Health Emergency of International Concern, putting it in the same league as polio and COVID-19.

In May, clusters of monkeypox cases were detected in the UK and Europe. Since then, 16,836 cases of monkeypox have emerged in 74 countries, according to the US Centers for Disease Control and Prevention. Monkeypox outbreaks have historically been much smaller, and occurred in central and western Africa.

“The cases we are seeing are just the tip of the iceberg,” Albert Ko told the Associated Press. Ko is a professor of public health and epidemiology at Yale University. “The window has probably closed for us to quickly stop the outbreaks in Europe and the U.S., but it’s not too late to stop monkeypox from causing huge damage to poorer countries without the resources to handle it.”

There are two types of monkeypox circulating in humans. One is more serious, and has a 10 percent fatality rate — currently, it has only been detected in Africa. The version that seems to be driving the worldwide outbreak is a milder strain that is rarely fatal. Both versions cause a fever and a rash that can be painful. Monkeypox viruses can be transmitted through close contact with an infected person, or with infected bodily fluids, though scientists are still working to figure out what’s driving this wave of cases. The vast majority of cases in the current outbreak have occurred in men, and particularly in men who have sex with men, the WHO says. It notes that there has also been an uptick in cases in parts of Africa, where monkeypox patients include more women and children.

The WHO’s declaration could theoretically help countries bolster their public health response. It came with recommendations for how different countries should respond to the virus, whether they’ve detected cases already or not. Unlike COVID-19, monkeypox is a known quantity. There are tests and vaccines for this virus, and while there aren’t specialized treatments, some antivirals may work on the disease.

But the declaration itself has been a matter of debate for weeks now, especially because the virus appears to be having very different impacts on populations around the world. In Europe and the US, the virus is mild, and countries are buying up vaccines to distribute. In Africa, where cases have been fewer, but more serious, no vaccines have been sent out, the Associated Press reports.

Back in June, a panel of experts made the controversial decision that monkeypox did not qualify as a global public health emergency. The WHO defines this kind of emergency as “an extraordinary event, which constitutes a public health risk to other States through international spread, and which potentially requires a coordinated international response.” Today, the panel met again and was split as to whether or not monkeypox actually met those criteria.

The WHO panel members who were in favor of today’s declaration felt that it did meet those standards. They also noted that they had a “moral duty to deploy all means and tools available to respond to the event,” citing LGBTI+ leaders from around the world who are especially concerned that this disease is disproportionately affecting their communities. They pointed out that “the community currently most affected outside Africa is the same initially reported to be affected in the early stages of HIV/AIDS pandemic.” During the early days of that pandemic, the disease was ignored and stigmatized because it was associated with gay men.

Panel members who were not in favor said that the conditions of the outbreak had remained unchanged since they last met in June, when they decided not to issue an emergency declaration. They pointed to the fact that the disease in most of the world has been mild, and might be starting to stabilize in some countries. They also mentioned being concerned about the stigma an emergency health declaration might cause “especially in countries where homosexuality is criminalized.” Another concern was the still extremely limited global supply of monkeypox vaccines. People who opposed the declaration said they were worried that declaring an emergency might increase demand for the vaccine, even in people who are not at risk, putting a strain on the vaccine supply.

In the end, even though the panel was split, Tedros Adhanom Ghebreyesus, the director general of the WHO decided it was worth declaring an emergency. “We have an outbreak that has spread around the world rapidly through new modes of transmission, about which we understand too little, and which meets the criteria” Tedros said, according to The New York Times.